The invention relates to a hydrodynamic coupling, in particular having the features of the preamble of claim 1.
Hydrodynamic couplings are known in different embodiments from a multitude of publications. As representative, reference is made to Volth publication Nr. CR 277d 5.00 1000. This discloses a hydrodynamic coupling with an integrated oil-supply arrangement. This includes a primary wheel functioning as a pump wheel and a secondary wheel; assigned to the primary wheel is a so-called shell that is connected to the latter in a rotationally-fixed manner and surrounds the secondary wheel in the axial extension and at least over a portion of the radial extension. The shell displays passages in the region of its outer periphery, in particular in the region of the radially outer dimensions, which passages make possible the passing of operating medium from the shell into an additional catch shell that is coupled in a rotationally-fixed manner to this shell, from which additional shell the operating medium is conducted by means of a dynamic pressure pump in a closed circuit during the operation of the hydrodynamic coupling. In the case of the disconnection of the hydrodynamic coupling, by virtue of the arrangement of the passages in the shell there occurs by effect of centrifugal force an emptying of the toroidal work chamber and, conditioned by this, an emptying of the intermediate chamber defined by the shell. The complete emptying thereby achieved is, however, not desired in every case, in particular in application cases that due to frequently alternating filling and emptying processes require a very quick filling process in order to ensure a rapid transfer of torque.
The invention is thus based on the task of further developing, with low structural and production technology expense, a hydrodynamic coupling of the type specified in the introduction such that during operation the filling via the inlet is sustained, while the outflow through the nozzles is ensured, and that during the standstill of the coupling a partial filling is ensured. In this way:
the fill supply can be shortened in the case of a desired quick placing into operation and/or
in each operating state of the hydrodynamic coupling the power transmission between the rotor parts can be ensured.
The solution according to the invention is characterized through the features of claim 1. Advantageous configurations are specified in the dependent claims.
The hydrodynamic coupling comprises a primary wheel and a secondary wheel that together form a toroidal working chamber. Connected in a rotationally fixed manner to the primary wheel is a shell (referred to as the first shell in the following) which surrounds the secondary wheel in the axial extension and at least over a portion of the radial extension while forming an intermediate chamber. The shell displays at least one passage that is arranged in the radially outer region of the shell. According to the invention, coupled to the shell and/or the primary wheel is an additional shell that forms a second intermediate chamber, which is connected to the first intermediate chamber via the passages in the first shell. The second shell likewise displays in its radially outer region at least one passage that connects the second intermediate chamber with the environment or with the interior of a hydrodynamic coupling formed by a housing or, in the case of installation in a drive apparatus, the housing of the latter. According to the invention, furthermore the passages in the first shell and the second shell are, when viewed in the peripheral direction, offset in relation to each other, so that the operating medium after emerging into the first shell is not immediately flung off into the environment, but rather must cover a particular flow route in the second intermediate chamber before it exits entirely from the hydrodynamic coupling.
According to an especially advantageous configuration, the passages in the first shell and in the second shell are rotated 180 degrees with respect to each other in the direction of the periphery. Viewed in the radial direction starting from the axis of rotation, the passages here lie either on the same radius or the passage on the second shell lies on a larger radius than the passage on the first shell. Based on their spatial arrangement with respect to each other, one can also speak of the first shell as the inner shell and the second shell as the outer shell.
The solution according to the invention makes possible the fact that even during standstill or still during the emptying process of the hydrodynamic coupling a certain fill amount always remains in the hydrodynamic coupling, by virtue of the favorable, restricted guidance in the second, i.e. outer shell up to the exit point. This partial filling in the standstill condition offers the advantage that, when operation of the hydrodynamic coupling is restarted, a certain supply of operating medium is already available, which supply need not first be provided via the operating medium supply system, which can lead to a temporal delay during the filling. In particular for application cases that are here characterized through a rapid alternation between startup of operation and shutdown of operation of the hydrodynamic coupling, this solution offers a considerable advantage in that the forces, due to the operating medium, opposed to the startup of operation are negligibly small. Special filling pumps with especially high pumping capacity are not needed.
Regarding the concrete embodiment of the second, i.e. outer shell and therewith the assignation of the intermediate chamber to the first, i.e. inner shell, and/or to the first intermediate chamber formed by the inner shell, several possibilities exist. According to the structural space conditions the following solutions are embraced:
a) arrangement of the second intermediate chamber, formed by the second or outer shell, in the axial direction next to the first intermediate chamber formed by the first or inner shell
b) arrangement of the second, outer intermediate chamber on the outside in the radial direction, that is, enclosing the first intermediate chamber in the radial direction
In the first-mentioned case, the intermediate chamber extends preferably in the radial direction into the region of the radial extent of the first intermediate chamber, that is to say, no gradation is present between the first and the second shells, which are arranged next to each other. Striven for in the second case is preferably an extending of the second intermediate chamber in the axial direction in a magnitude that corresponds to the maximal extension of the first intermediate chamber in the axial direction. With these two solutions, a coupling configuration that is optimal with respect to the possible ventilation losses can be worked out. However, it is also conceivable to realize a combination of both solutions, so that the second, outer intermediate chamber encloses, as it were, the first intermediate chamber in both the axial and radial directions, in which both are separated by the wall of the first, inner shell.
The passages, in the simplest case, can be embodied as perforation bores. However, these can also be provided with cross-sectional variations, according to desired additional effects. This applies also to the alignment of the passages. These can be radially aligned or at an angle with respect to a perpendicular to the rotational axis.
Regarding the concrete structural configuration, especially the connection, of the second, outer coupling shell to the first, inner coupling shell and/or to the primary wheel, there exist a multitude of possibilities, which, however, lie within the normal scope of activity of the competent specialist. The outer, second intermediate chamber is here present as a ring chamber or ring-shaped channel corresponding to the configuration of the second shell.